Alongside his journalistic activities, he worked closely with Sartre and adopted an existentialist approach to Marxism, leading him to emphasize the questions of alienation and of liberation in the framework of existential experience and an analysis of social systems from the viewpoint of individual experience. This intellectual framework formed the basis of his first books, Le Traître (Le Seuil, 1958, prefaced by Sartre[3]), La Morale de l'histoire (Le Seuil, 1959) and the Fondements pour une morale (Galilée, 1977, published fifteen years later), which he signed for the first time as André Gorz, from the German name of the now Italian city (Görz) where the eyeglasses given to his father by the Austrian Army were made.

He directly addressed himself to trade-unions in Stratégie ouvrière et néocapitalisme (Le Seuil, 1964), where he criticized capitalisteconomic growth and expounded on the various strategies open to trade-unions. The same year, he quit L'Express along with Serge Lafaurie, Jacques-Laurent Bost, K.S. Karol and Jean Daniel to found Le Nouvel Observateur weekly (using the pseudonym of Michel Bosquet).

Deeply affected by May '68, Gorz saw in these events a confirmation of his existential-Marxist posture, which joined the students' criticisms towards institutional and state organization (State, School, Family, Firm, etc.). Thereafter, Ivan Illich's thesis on education, medicine or the abolition of wage labour became the focus of his attention. He published one of Illich's speech in Les Temps Modernes in 1961, before meeting him in 1971 in Le Nouvel Observateur at the occasion of his publication of Deschooling Society (Une Société sans école). He later published a resume of Illich's Tools for Conviviality (1973) under the title Libérer l'avenir (Free Future). His links with Illich were strengthened after a trip to California in 1974, where he wrote several articles for Le Nouvel Observateur discussing Illich's thesis.[6]

Gorz's evolution and political and philosophical stances led to some tensions with his colleagues on Le Temps Moderne, for which he had assumed the chief editorial responsibilities in 1969. In April 1970, his article Destroy the University (Détruire l'Université) provoked the resignation of Pontalis and Pingeaud. Gorz also criticized a Maoist tendency present in the journal since 1971 (and supported by Sartre). Finally, in 1974 Gorz resigned as the editor of Les Temps Modernes, following a disagreement concerning an article about the Italian autonomist group Lotta Continua. At the same time, he found himself he was forced to the periphery of Le Nouvel Observateur, being replaced by more classically-oriented economists, while he followed at the same time a campaign against nuclear industry — to which EDF, the state electricity firm, replied by withdrawing advertisements from the weekly. Following the weekly's refusal to let him publish a special issue on the nuclear issue, he published it in the Que Choisir? consumers' magazine.

In the same period, Gorz was becoming a leading figure of political ecology, his ideas being spread in particular by the ecologist monthly Le Sauvage, founded by Alain Hervé, the creator of the French section of the Friends of the Earth. In 1975, he published Ecologie et politique (Galilée, 1975), which included the essay Ecologie et liberté, "one of the foundational texts of the ecologic problematic" (Françoise Gollain[7]).

He was also influenced by Louis Dumont in considering Marxism and Liberalism to be two versions of economist thought. Gorz then opposed himself both to hedonistindividualism and utilitarianism and to materialist and productivist collectivism, defending a humanist version of ecology similar to social ecology which is opposed to deep ecology. Gorz's ecologism, however, remained linked to a critique of Capitalism, as he called for an "ecological, social and cultural revolution which would abolish the constraints of Capitalism".[8]

A year before the election of the left's candidate, François Mitterrand, to the presidency, he published Adieux au prolétariat (Galilée, 1980 - Farewell to the Proletariat) where he criticized the cult of the Proletarian class in Marxism, arguing that changes in science and technology now made it impossible for the working-class to be the sole, or even primary, revolutionary agent. Although the book was not well received among the French Left, it did receive attention from younger readers. Soon after Sartre's death in that same year Gorz left the editorial board of Les Temps Modernes. In Les Chemins du paradis (Galilée, 1983) Gorz remained critical of the Marxist orthodoxy of the time, using Marx's own analysis in the Grundrisse to argue for the need of the political left to embrace the liberatory potential that the increasing automation of factories and services offered as a central part of the socialist project. In 1983 he had a falling out with the pacifist movements when he refused to oppose the deployment of Pershing II missiles by the United States in West Germany. The same year, he resigned from Le Nouvel Observateur. In the 1990s and 2000s, the journals Multitudes,[9]EcoRev' which will publish the last article in French "la fin du capitalisme a déjà commencé"[10] and Entropia published his articles.

Gorz was also critical of the Post-Structuralism and Postmodernism of thinkers such as Antonio Negri. His point of view was rooted in early Marxist humanist thinking. Liberation from wage-slavery and social alienation was still one of his goals, even in his later works. He never became an abstract theorist; his reasoning usually concluded with proposals for how to act to make changes. In Métamorphoses du travail (Galilée, 1988 - Metamorphosis of Labour), Gorz argued that capitalism used personal investments from the worker which were not paid back. As such, he became an advocate of Guaranteed basic income, independent from "labour." He made such a proposal in his book, Critique of Economic Reason, 1989, and argued:

"From the point where it takes only 1,000 hours per year or 20,000 to 30,000 hours per lifetime to create an amount of wealth equal to or greater than the amount we create at the present time in 1,600 hours per year or 40,000 to 50,000 hours in a working life, we must all be able to obtain a real income equal to or higher than our current salaries in exchange for a greatly reduced quantity of work. In practice, this means that in the future we must receive our full monthly income every month even if we work full-time only one month in every two or six months in a year or even two years out of four, so as to complete a personal, family or community project, or experiment with different lifestyles, just as we now receive our full salaries during paid holidays, training courses, possibly during periods of sabbatical leave, and so forth...."

He pointed out that:

in "contrast to the guaranteed social minimum granted by the state to those unable to find regular paid work, our regular monthly income will be the normal remuneration we have earned by performing the normal amount of labour the economy requires each individual to supply. The fact that the amount of labour required is so low that work can become intermittent and constitute an activity amongst a number of others, should not be an obstacle to its being remunerated by a full monthly income throughout one's life. This income corresponds to the portion of socially produced wealth to which each individual is entitled by virtue to their participation in the social process of production. It is, however, no longer a true salary, since it is not dependent on the amount of labour supplied (in the month or year) and is not intended to remunerate individuals as workers."

Gorz and his wife, Dorine, committed suicide together in his home in Vosnon (Aube). His wife had been diagnosed with a terminal illness and they had already said that neither wanted to survive the other's death. Their bodies were found on the 24th of September 2007 by a friend, both having died after a lethal injection.[3][11] His book Lettre à D. Histoire d'un amour (Galilée, 2006) was dedicated to his wife, and was in fact a way for him to tell of the love he had for her.